Boxford 250 PC conversion

[mataf01]

Hello ...whoops .....I don't follow this group. It was just something I happened to come across in 2015 and could provide a little info.
Sorry Patrick, yes I have the schematic for your machine with 2HP DC spindle drive. I'm not sure if you visit this site anymore, and I am not sure if it would be prudent to put my email address here. I'll try connecting by some other method.
For "servo_Ian", the motor frames are Nema 34 for both axis and toolchanger. You can determine the motor rating by the motor lengths which are all the same at 94mm. I believe it is in the 1,000 in-oz area (62 in-lbs, 7 Nm) You can do whatever other conversions from here. If you insist on servos, you will have serious problems with refitting as they are longer than open-loop steppers. This may sound incidental, but if you have the 2HP machine, your X-axis will hit the guard at the extreme travel, and you will have the same problem on Z-axis. You don't need a servo on the tool changer.
I am in the process of converting the 3HP. I did the first conversion with Camsoft. I won't make that mistake again. When a software adjustment was needed/made, then "something that did work" now no longer worked. This went on and on for years. Now, the G74 which they claim is standard, no longer works .....and they want more money to fix. No thanks. I done with the Camsoft mickey-mousing around. I will be going with Centroid. Their boards are ready to go as is the major portion of their software. One other primary change will be a very significant change in the spindle encoder. Complete replacement for an industrial encoder with standard very high resolution.
I was just curious about what Boxford is doing these days with innovation and technology with their machines. Well it appears very British. They have regressed. Their solid CNC machines are gone. It would appear their management is not going to be compete with the rest of the world. The machines are now only for teaching principles. Students will not be taught about "material removal", or "material removal rates". These machines are now only for plastic and plastic chess sets.
Just saw a "Boxford Promotional Video" of their "purpose built" plant ...with some "princess" proudly standing at front-and-center at the end ....with what may have been all 42 employees. ....sad.

Hello, Wayne888 sorry for the very late reply.
I've been very hill (3years) since I posted the message you've answered and I have left everything down. But as I start to recover, I'm back into the game. If you still have the schematics of the Boxford 250 pc I would appreciate If I could have a copy . I'm planing to go with centroid acorn, new steppers and drivers but thinking to replace the spindle motor with a 1.8 KW DMM tech servo motor with a 1 to 1 ratio.
Thank you
Patrick

 

[HMEL]

Hi,

I am starting this thread as a record of the conversion a of Boxford CNC 250 PC lathe I own. The lathe is approx 20 years old and has had very little use. the lathe works fine using the manual controls. I have set up a PC with Mach 3 and have been unable to get any response from the lathe. The original computer system is propriety and Boxford has little interest in sharing the older lathe info I have decided to retrofit the lathe with a controller that will communicate with Mach 3 and the stepper and servo spindle drivers.

I have selected the CSLAB CSMIO/IP-S Motion Controller which I have just recently received from Poland and I am busy with my head buried in the manual at the moment.

I plan to update my progress about once a week with the next installment being a plan and circuit diagram of the proposed changes. I have an IT background but CNC is new to me and information on the hardware side of things has been difficult the find. I have been relying on the Mach 3 manual (excellent) and the CSMIO/IP-S manual (excellent) as well as locating the original driver specs on the web.

I had a few conversations with demonstrators at the recent Melbourne Model Engineering Exhibition and they indicated that they considered configuring a CNC lathe was more difficult than a CNC milling machine. I have a habit of jumping in at the deep end so we will see if I can swim.

I welcome feedback from forum members and hope this thread will become a useful record of the issues encountered retrofitting a Boxford CNC lathe.

I have looked carefully at doing something similar to a smaller bench lathe. As far as the software and electronics it is no more difficult then a mill. However the challenge lies in coordinating the spindle with the lead screw and insuring the lead screw driver has enough power. Other then the ability to thread is some ways it appears simpler then a mill as the number of axis are reduced to two. The distance measuring equipment for position is also a challenge as the options appear to be many. I look forward to your future posts to see how you approach these problems.

 

[servo_Ian]

Hi all
A little update to say very little. On my PC250 progress story, well, it has actually been mostly VMC300 as it happens. The VMC300 is now up and running under an Ethernet Smoothstepper and Mach4. I learnt a lot whilst doing this and am happy with the results. I am still working on some refinements like an 11 position dial (the original rotary knob) to gray code pcb for manual override etc.
On the PC250 though, I have refitted the original steppers and bought some drivers for them. I have updated the csmio-ip s and will soon plug it all together and start making stuff move. It'll still probably be slow work with my job competing for time but at least it is moving again

 

[servo_Ian]

A small update on the PC250 progress. I have mapped out 90% of the wiring with only one sensor to find. I have the stepper motors all working under the CSMIO/IP-S and all the relevant sensors connected. Only one needed replacement so far which was nice.
Some stuff will need rethinking completely for example the optical spindle speed sensor wheel. This will need to become an incremental encoder with a differential interface. A far cry from the 50 notches + one index mark of the original. This is one job for later though.
A bit of programming, lots of testing and documentation and I'll soon move onto the spindle. Initially I'll try to reuse the original VFD but I have a new one if that defeats me.
I have also been replacing the oil lines as I go, they are terribly brittle and discoloured so no choice really.
I am updating progress on my website (not sure if I can link it here?). It'll probably come up in Google if you look searching the two boxford machines I have mentioned

 

[servo_Ian]

Got the z axis limit switches all installed and configured in Mach4, very pleased with that.
Now to investigate the VFD and/or start installing x limit switches plus a tool 1 proximity switch so I can home everything

 

[Wayne888]

Hello, Wayne888 sorry for the very late reply.
I've been very hill (3years) since I posted the message you've answered and I have left everything down. But as I start to recover, I'm back into the game. If you still have the schematics of the Boxford 250 pc I would appreciate If I could have a copy . I'm planing to go with centroid acorn, new steppers and drivers but thinking to replace the spindle motor with a 1.8 KW DMM tech servo motor with a 1 to 1 ratio.
Thank you
Patrick

Hello ...me too ...late reply. I just don't actively chase after any information for "Boxford 250PC". A good decision (in my opinion) going with Centroid. Let me know how this turned out. This message is being generated on 25FEB22. I am not confident this forum reveals correct dates properly. I would prefer to provide my email and you can connect up directly so I can send you the schematics should you still need them. Let me know .....whenever you come back to this site.
" tarlingw at yahoo dot com " should you ever get this message.

 

[HMEL]

I do not know if this will give you any useful information but I based my VFD conversion on Clough42 on youtube. He also has developed rather interesting approach to coordinating the spindle with the lead screw. He is able to do metric or imperial threads with simple settings which I am very tempted to copy.

 

[dazz]

Hi
If Cough42 used electronic lead screw, this has limitations. When I last looked, the ELS only sensed spindle rotation once per rpm. It takes a few rotations to sync with the lead screw. That can mess up the start of the threads. Any interrupted cuts (keyways) will also mess things up.
It is a great project if there is no alternative.

 

[Yealland]

I can't offer anything on the rest of this thread but I did copy Clough 42's ELS on my small lathe. In his design the lathe spindle drives a quadrature encoder that generates 1024 pulses/evolution. This allows leadscrew syncing up to quite high RPMs as long as the microcontroller & software can keep up. Hope this is of some help.

 

[dazz]

I can't offer anything on the rest of this thread but I did copy Clough 42's ELS on my small lathe. In his design the lathe spindle drives a quadrature encoder that generates 1024 pulses/evolution. This allows leadscrew syncing up to quite high RPMs as long as the microcontroller & software can keep up. Hope this is of some help.

Hi
OK that makes a big difference. Any closed loop feedback control system produces an error signal that is the difference between a reference and the output. It would be really interesting to see the error signal from Clough 42 ELS